Detecting single event upsets and stuck-at faults in RAM-based data path controllers

ABSTRACT

In one embodiment, a method includes receiving data comprising a plurality of data elements; creating a binary sequence comprising a plurality of bonus bits using a first binary sequence generator; using a first exclusive-or module to provide a XOR calculation using bits of each data element of the data with a bonus bit from the binary sequence; passing each data element along with its corresponding parity bit to an input of a data path; receiving each data element along with its corresponding parity bit at an output of the data path; creating the binary sequence using a second binary sequence generator; using a second XOR module to XOR together bits of each data element along with its corresponding parity bit and a bonus bit from the binary sequence to produce a result; and analyzing the result to determine whether an error has occurred to the data in the data path.

BACKGROUND

The present invention relates to data path management, and morespecifically, this invention relates to detecting single event upsetsand stuck-at faults in random access memory (RAM)-based data pathcontrollers.

Typically, a stuck-at fault is a fault-model that may be used to imitatea manufacturing defect in integrated circuit (IC)-based memory modules,such as those which utilize RAM. Electronic communications, control, andstorage systems often require controllers with complex data pathsinvolving multiple memory modules, such as data buffers andfirst-in-first-out (FIFO) buffers. The underlying memory elements forthese modules typically utilize RAM. The integrity of the data beingpassed through RAM-based data paths is vulnerable to corruption from twokinds of faults: soft errors (single-event upsets) and hard errors(e.g., stuck-at faults and bridging faults). Field Programmable GateArray (FPGA)-based systems are vulnerable to some additional failuremechanisms: both soft and hard failures in the configuration memoriesthat define their operation.

Systems typically employ methods for ensuring data integrity end-to-end,depending on the criticality of delivering pristine data and theprobability of encountering failures. Even so, lower level dataintegrity checks are often used to detect failures quickly and toidentify their location, so that the system has sufficient data topursue an appropriate fault recovery strategy (e.g., reset, reprogram,remove from service, etc.).

One method for detecting single-bit data failures is parity generationand checking. This method involves applying exclusive-or (XOR) to allthe bits in each data word, storing the single-bit result with the dataword, then checking the XOR result when data is read. RAM is oftenconstructed with data widths that allow one parity bit per byte of datato accommodate a data parity scheme. Address faults (e.g., stuck-at orbridging faults affecting the address lines of RAM) are often covered byapplying XOR to the address used to store each data word and includingthe result in the calculation of the per-word data parity. Of course,this assumes that the address used to write each data word to RAM is thesame as the address used to read each word from RAM.

Generating and checking parity at each RAM in the data path may beunnecessarily expensive. It is often sufficient to isolate a failure toa more general location, such as somewhere in this data path, where thedata path may have multiple stages of memory elements. A scheme wheredata is calculated at the start of the data path and passed along to theend for checking, would be an inexpensive method for checking single-bitsoft and hard failures. Such a method, however, fails to cover a largeset of faults, including address faults, that may break the sequence inwhich data traverses the data path. Adding address parity at the frontend for checking at the back end also does not provide a generalsolution, since input and output addressing may not correspond.

A data checking method that checks both data and sequence is the cyclicredundancy check (CRC). As data enters the communication or storagechannel, a CRC value is calculated for the data sequence usingpolynomial division. This value is appended to the data sequence. At theoutput of the channel, the entire sequence, including both original dataand CRC value, is subjected to the same polynomial division and checkedagainst a constant value (usually zero). A non-matching result indicatesan error in the data sequence. Such an approach covers both data andaddress faults.

However, many data path controllers involve modification of the datamidstream. For example, storage controllers supporting redundant arrayof independent disk (RAID) reconstruction rebuild data by applying XORto data from multiple pages in the RAID stripe. Restoring the CRC valueduring the rebuild process would require a significant increase incomplexity (for example, recalculating CRC during the final stage ofrebuilding, or storing the CRC values for every page in the stripe).

BRIEF SUMMARY

In one embodiment, a computer program product includes a non-transitorycomputer readable storage medium having program instructions embodiedtherewith, where the program instructions are readable by a processor,executable by the processor, or readable and executable by the processorto cause the processor to receive, by the processor, data comprising aplurality of data elements, each data element comprising one byte;create, by the processor, a binary sequence comprising a plurality ofbonus bits using a first binary sequence generator, a total length ofthe binary sequence being equal to or greater than a maximum burst sizeof the data, wherein the first binary sequence generator comprises oneor more linear feedback shift registers (LFSRs); use, by the processor,a first parity module to provide a parity calculation using bits of eachdata element of the data with a bonus bit from the binary sequence, theparity calculation producing a parity bit for each data element; pass,by the processor, each data element along with its corresponding paritybit to an input of a data path; receive, by the processor, each dataelement along with its corresponding parity bit at an output of the datapath, wherein data exits the output of the data path in burst sizes thatare equal to burst sizes of the data that entered the input of the datapath; create, by the processor, the binary sequence using a secondbinary sequence generator, wherein the second binary sequence generatoris matched to the first binary sequence generator; use, by theprocessor, a second parity module to produce a result based on bits ofeach data element along with its corresponding parity bit and a bonusbit from the binary sequence; and analyze, by the processor, the resultto determine whether an error has occurred to the data in the data path.

In another embodiment, a system includes a hardware processor; and logicintegrated with the hardware processor, executable by the hardwareprocessor, or integrated with and executable by the hardware processor,the logic being configured to: receive data comprising a plurality ofdata elements, each data element comprising one byte; create a binarysequence comprising a plurality of bonus bits using a first binarysequence generator, a total length of the binary sequence being equal toor greater than a maximum burst size of the data, wherein the firstbinary sequence generator comprises one or more linear feedback shiftregisters (LFSRs); use a first parity module to provide a paritycalculation using bits of each data element of the data with a bonus bitfrom the binary sequence, the parity calculation producing a parity bitfor each data element; pass each data element along with itscorresponding parity bit to an input of a data path; receive each dataelement along with its corresponding parity bit at an output of the datapath, wherein data exits the output of the data path in burst sizes thatare equal to burst sizes of the data that entered the input of the datapath; create the binary sequence using a second binary sequencegenerator, wherein the second binary sequence generator is matched tothe first binary sequence generator; use a second parity module toproduce a result based on bits of each data element along with itscorresponding parity bit and a bonus bit from the binary sequence; andanalyze the result to determine whether an error has occurred to thedata in the data path.

In yet another embodiment, a method includes receiving, by a processor,data comprising a plurality of data elements, wherein each data elementis one byte in length; creating, by the processor, a binary sequencecomprising a plurality of bonus bits using a first binary sequencegenerator, a total length of the binary sequence being equal to orgreater than a maximum burst size of the data; using, by the processor,a first exclusive- or (XOR) module to provide a XOR calculation usingbits of each data element of the data with a bonus bit from the binarysequence, the XOR calculation producing a parity bit for each dataelement; passing, by the processor, each data element along with itscorresponding parity bit to an input of a data path; receiving, by theprocessor, each data element along with its corresponding parity bit atan output of the data path, wherein data exits the output of the datapath in burst sizes that are equal to burst sizes of the data thatentered the input of the data path; creating, by the processor, thebinary sequence using a second binary sequence generator, wherein thesecond binary sequence generator is matched to the first binary sequencegenerator; using, by the processor, a second XOR module to XOR togetherbits of each data element along with its corresponding parity bit and abonus bit from the binary sequence to produce a result; and analyzing,by the processor, the result to determine whether an error has occurredto the data in the data path comprising determining, by the processor,whether the result is zero, wherein a zero result indicates that noerror occurred to the data while in the data path, wherein a non-zeroresult indicates that an error occurred to the data while in the datapath.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a network architecture, in accordance with oneembodiment.

FIG. 2 shows a representative hardware environment that may beassociated with the servers and/or clients of FIG. 1, in accordance withone embodiment.

FIG. 3 illustrates a tiered data storage system in accordance with oneembodiment.

FIG. 4 shows a system according to one embodiment.

FIG. 5 shows a flowchart of a method according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified. It will be further understood thatthe terms “comprises” and/or “comprising,” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

The following description discloses several preferred embodiments ofsystems, methods and computer program products that address deficienciesin data parity and cyclic redundancy check (CRC) schemes by providing ageneral low-cost method for end-to-end parity generation and checkingthat the scheme provides coverage for both data and sequencing faults.Furthermore, simple modifications to the data in midstream is allowed,such as during a redundant array of independent disk (RAID) reconstructscenario.

In one general embodiment, a system includes a processor and logicintegrated with and/or executable by the processor, the logic beingconfigured to receive data including a plurality of data elements, eachdata element having one or more bits, and pass each data element alongwith a corresponding parity bit to an input of a data path, a firstbinary sequence generator configured to create a binary sequence havinga plurality of bonus bits, wherein a total length of the binary sequenceis equal to or greater than a maximum burst size of the data, and afirst parity module configured to provide a parity calculation usingbits of each data element of the data with a bonus bit from the binarysequence to produce a parity bit for each data element.

In another general embodiment, a method includes receiving data having aplurality of data elements, each data element including one or morebits, creating a binary sequence having a plurality of bonus bits usinga first binary sequence generator, a total length of the binary sequencebeing equal to or greater than a maximum burst size of the data, using afirst parity module to provide a parity calculation using bits of eachdata element of the data with a bonus bit from the binary sequence, theparity calculation producing a parity bit for each data element, andpassing each data element along with its corresponding parity bit to aninput of a data path.

In yet another general embodiment, a computer program product includes acomputer readable storage medium having program instructions embodiedtherewith, the program instructions readable and/or executable by aprocessor to cause the processor to: receive, by the processor, datahaving a plurality of data elements, each data element including one ormore bits, create, by the processor, a binary sequence having aplurality of bonus bits using a first binary sequence generator, a totallength of the binary sequence being equal to or greater than a maximumburst size of the data, use, by the processor, a first exclusive-or(XOR) module to provide a XOR calculation using bits of each dataelement of the data with a bonus bit from the binary sequence, the XORcalculation producing a parity bit for each data element, and pass, bythe processor, each data element along with its corresponding parity bitto an input of a data path.

FIG. 1 illustrates an architecture 100, in accordance with oneembodiment. As shown in FIG. 1, a plurality of remote networks 102 areprovided including a first remote network 104 and a second remotenetwork 106. A gateway 101 may be coupled between the remote networks102 and a proximate network 108. In the context of the presentarchitecture 100, the networks 104, 106 may each take any formincluding, but not limited to a LAN, a WAN such as the Internet, publicswitched telephone network (PSTN), internal telephone network, etc.

In use, the gateway 101 serves as an entrance point from the remotenetworks 102 to the proximate network 108. As such, the gateway 101 mayfunction as a router, which is capable of directing a given packet ofdata that arrives at the gateway 101, and a switch, which furnishes theactual path in and out of the gateway 101 for a given packet.

Further included is at least one data server 114 coupled to theproximate network 108, and which is accessible from the remote networks102 via the gateway 101. It should be noted that the data server(s) 114may include any type of computing device/groupware. Coupled to each dataserver 114 is a plurality of user devices 116. Such user devices 116 mayinclude a desktop computer, lap-top computer, hand-held computer,printer or any other type of logic. It should be noted that a userdevice 111 may also be directly coupled to any of the networks, in oneembodiment.

A peripheral 120 or series of peripherals 120, e.g., facsimile machines,printers, networked and/or local storage units or systems, etc., may becoupled to one or more of the networks 104, 106, 108. It should be notedthat databases and/or additional components may be utilized with, orintegrated into, any type of network element coupled to the networks104, 106, 108. In the context of the present description, a networkelement may refer to any component of a network.

According to some approaches, methods and systems described herein maybe implemented with and/or on virtual systems and/or systems whichemulate one or more other systems, such as a UNIX system which emulatesan IBM z/OS environment, a UNIX system which virtually hosts a MICROSOFTWINDOWS environment, a MICROSOFT WINDOWS system which emulates an IBMz/OS environment, etc. This virtualization and/or emulation may beenhanced through the use of VMWARE software, in some embodiments.

In more approaches, one or more networks 104, 106, 108, may represent acluster of systems commonly referred to as a “cloud.” In cloudcomputing, shared resources, such as processing power, peripherals,software, data, servers, etc., are provided to any system in the cloudin an on-demand relationship, thereby allowing access and distributionof services across many computing systems. Cloud computing typicallyinvolves an Internet connection between the systems operating in thecloud, but other techniques of connecting the systems may also be used.

FIG. 2 shows a representative hardware environment associated with auser device 116 and/or server 114 of FIG. 1, in accordance with oneembodiment. Such figure illustrates a typical hardware configuration ofa workstation having a central processing unit 210, such as amicroprocessor, and a number of other units interconnected via a systembus 212.

The workstation shown in FIG. 2 includes a Random Access Memory (RAM)214, Read Only Memory (ROM) 216, an I/O adapter 218 for connectingperipheral devices such as disk storage units 220 to the bus 212, a userinterface adapter 222 for connecting a keyboard 224, a mouse 226, aspeaker 228, a microphone 232, and/or other user interface devices suchas a touch screen and a digital camera (not shown) to the bus 212,communication adapter 234 for connecting the workstation to acommunication network 235 (e.g., a data processing network) and adisplay adapter 236 for connecting the bus 212 to a display device 238.

The workstation may have resident thereon an operating system such asthe Microsoft Windows® Operating System (OS), a MAC OS, a UNIX OS, etc.It will be appreciated that a preferred embodiment may also beimplemented on platforms and operating systems other than thosementioned. A preferred embodiment may be written using XML, C, and/orC++ language, or other programming languages, along with an objectoriented programming methodology. Object oriented programming (OOP),which has become increasingly used to develop complex applications, maybe used.

Now referring to FIG. 3, a storage system 300 is shown according to oneembodiment. Note that some of the elements shown in FIG. 3 may beimplemented as hardware and/or software, according to variousembodiments. The storage system 300 may include a storage system manager312 for communicating with a plurality of media on at least one higherstorage tier 302 and at least one lower storage tier 306. The higherstorage tier(s) 302 preferably may include one or more random accessand/or direct access media 304, such as hard disks in hard disk drives(HDDs), nonvolatile memory (NVM), solid state memory in solid statedrives (SSDs), flash memory, SSD arrays, flash memory arrays, etc.,and/or others noted herein or known in the art. The lower storagetier(s) 306 may preferably include one or more lower performing storagemedia 308, including sequential access media such as magnetic tape intape drives and/or optical media, slower accessing HDDs, sloweraccessing SSDs, etc., and/or others noted herein or known in the art.One or more additional storage tiers 316 may include any combination ofstorage memory media as desired by a designer of the system 300. Also,any of the higher storage tiers 302 and/or the lower storage tiers 306may include some combination of storage devices and/or storage media.

The storage system manager 312 may communicate with the storage media304, 308 on the higher storage tier(s) 302 and lower storage tier(s) 306through a network 310, such as a storage area network (SAN), as shown inFIG. 3, or some other suitable network type. The storage system manager312 may also communicate with one or more host systems (not shown)through a host interface 314, which may or may not be a part of thestorage system manager 312. The storage system manager 312 and/or anyother component of the storage system 300 may be implemented in hardwareand/or software, and may make use of a processor (not shown) forexecuting commands of a type known in the art, such as a centralprocessing unit (CPU), a field programmable gate array (FPGA), anapplication specific integrated circuit (ASIC), integrated circuit (IC),etc. Of course, any arrangement of a storage system may be used, as willbe apparent to those of skill in the art upon reading the presentdescription.

In more embodiments, the storage system 300 may include any number ofdata storage tiers, and may include the same or different storage memorymedia within each storage tier. For example, each data storage tier mayinclude the same type of storage memory media, such as HDDs, SSDs,sequential access media (tape in tape drives, optical disk in opticaldisk drives, etc.), direct access media (CD-ROM, DVD-ROM, etc.), or anycombination of media storage types. In one such configuration, a higherstorage tier 302, may include a majority of SSD storage media forstoring data in a higher performing storage environment, and remainingstorage tiers, including lower storage tier 306 and additional storagetiers 316 may include any combination of SSDs, HDDs, tape drives, etc.,for storing data in a lower performing storage environment. In this way,more frequently accessed data, data having a higher priority, dataneeding to be accessed more quickly, etc., may be stored to the higherstorage tier 302, while data not having one of these attributes may bestored to the additional storage tiers 316, including lower storage tier306. Of course, one of skill in the art, upon reading the presentdescriptions, may devise many other combinations of storage media typesto implement into different storage schemes, according to theembodiments presented herein.

According to some embodiments, the storage system (such as 300) mayinclude logic configured to receive a request to open a data set, logicconfigured to determine if the requested data set is stored to a lowerstorage tier 306 of a tiered data storage system 300 in multipleassociated portions, logic configured to move each associated portion ofthe requested data set to a higher storage tier 302 of the tiered datastorage system 300, and logic configured to assemble the requested dataset on the higher storage tier 302 of the tiered data storage system 300from the associated portions.

Of course, this logic may be implemented as a method on any deviceand/or system or as a computer program product, according to variousembodiments.

According to one embodiment, a data parity generation and checkingscheme is used that covers both data integrity and sequence in whichdata flows through at least two memories in a data path. In thisembodiment, at the input(s) to the data path, parity is calculated overeach data element (the size of each data element, whether it is a byte,a word, a double word, etc.). Presumably, designers of particular parityschemes will choose an element size based on the trade-off betweenresource use and fault detection effectiveness, and therefore which sizeof data element used is variable in the embodiments described herein. Inaddition to the bits of the data element, a bonus bit from apseudo-random binary sequence (PRBS) generator is added to the XORcalculation of the parity bit. In more embodiments, some other suitablesource of single bonus bits which are unlikely to match sequences in thedata path may be used, as would be understood by one of skill in the artupon reading the present descriptions. One purpose of including thebonus bits in the parity calculation is to provide a sequence-dependentcomponent, which may then be decoded at a later time to ensure thesequence is correct. At the end of the data path where parity checkingis performed, the same source of bonus bits, such as PRBS, is includedin the parity check in order to back out the bonus bits and check theiraccuracy against the now produced bonus bit. If any fault in the datapath has disturbed either content of the data or sequence of the data,the parity check will fail.

This embodiment covers single faults per data element, as well as alarge sets of faults, single or multiple, that affect the data sequence.The latter might include faults in RAM addresses, address counters, FIFOcontrol logic, state machines that control memory access, etc. Inaddition, it is possible to cover faults in handling out-of-bandmetadata, additionally.

Bonus bit production, such as via PRBS generation, may be accomplishedusing linear feedback shift registers (LFSRs), which offer both low costand high performance. The LFSR's pseudo-random nature makes it highlyunlikely that sequence-affecting faults would go undetected due tosequence aliasing (having a fault produce a sequential component of theparity check that matches the PRBS).

Now referring to FIG. 4, a system 400 is shown according to oneembodiment. The system 400 may be used for detecting single event upsetsand stuck-at faults in RAM-based data path controllers, according to oneembodiment.

It may be assumed that data enters the data path 402 in bursts ofvarying sizes, but the sizes never exceed a predetermined and/orcalculated threshold, referred to as maximum burst size(MAX_BURST_SIZE). The threshold may be determined and/or based on anyconditions, parameters and/or properties of the system and/or componentsthereof. It may also be assumed that the data will exit the data path402 in bursts having the same size in which the data entered. Further,it may be assumed that at both the input 404 and the output 406 of thedata path 402, sufficient information is available to identify thebeginning of each burst.

As shown in FIG. 4, a first binary sequence generator 408 is positionedat the input 404 to the data path 402. The first binary sequencegenerator 408 may be configured to provide a binary sequence comprisinga plurality of bonus bits, the binary sequence having a length greaterthan or equal to the MAX_BURST_SIZE. In one embodiment, the first binarysequence generator 408 may include one or more LFSRs, each of which isconfigured to provide a pseudo-random binary sequence, with a totallength of all pseudo-random binary sequences from the one or more LFSRsbeing greater than or equal to the MAX_BURST_SIZE.

In an alternative embodiment, the first binary sequence generator 408may comprise a ROM or a patterned ROM in which values are retrieved inrandom or according to some predetermined pattern which would have anegligible chance of producing a binary sequence that matched any bitsof the data while in the data path.

At the beginning of each burst of data from the data stream, the firstbinary sequence generator 408 is initialized to a constant value. Aparity bit 412 is generated using a parity calculation in a first paritymodule 410 based on the bits of each incoming data element (byte, word,double word, etc.) and a bonus bit from the first binary sequencegenerator 408, to produce a parity bit 412. To provide a context, and byway of example only, the first parity module 410 will hereafter bedescribed as a first XOR module that applies an XOR calculation. Notethat other types of parity calculations may be used, as would be knownto one skilled in the art upon reading the present disclosure, such asan XNOR, etc.

Continuing with the example, the bits of each incoming data element(byte, word, double word, etc.) and a bonus bit from the first binarysequence generator 408 may be exclusive-ored (XOR'd) at the first XORmodule 410 to produce the parity bit 412 which accompanies the dataelement through the data path 402.

At the output 406 of the data path 402, the data element, itsaccompanying parity bit 412, and output from a second binary sequencegenerator 414 (which is matched to the first binary sequence generator408) are processed to produce a result by a second parity module 416,which is hereinafter referred to as a second XOR module 416, forexemplary purposes only. The result may be analyzed using an analysismodule 418 in one embodiment. When the result is null or zero (“0”), itmay indicate no errors in the data, in one embodiment. A non-zero resultmay indicate a failure somewhere in the data path 402, either in thecontent of the data or in the sequencing of the data through the datapath 402. Sequencing errors may occur when some portions of the datapropagate through the data path 402 more quickly than other portions,which would cause the contents of the data to be out of sequence at theoutput 406 of the data path 402.

In an alternate embodiment, a zero result may indicate a failuresomewhere in the data path 402, either in the content of the data or inthe sequencing of the data through the data path 402 while a result ofnull or zero (“0”) may indicate no errors in the data. Either way, aslong as the convention is set, e.g., whether 0 indicates no error orerror(s), and is understood by the components of the system, then theresult of the analysis module 418 will reveal whether any errors existin the data path 402.

One useful property of maximal-length pseudo-random binary sequencegenerators is that they produce full-length sequences regardless oftheir initial values. This property may be exploited to cover faultsaffecting out-of-band metadata normally outside the scope of data paritygeneration and checking.

For example, a system may be configured such that each burst of data hasa corresponding tag or label that is used to match each data burst withthe system command that produced it. Assume that the tag value isavailable at both the input and the output of the data path. By makingthe initial value of the binary sequence generator (such as a LFSR)dependent on the value of the tag, not only is the data and sequencechecked, but also the logic and memory involved in maintainingcorrespondence between the tag value and the data burst.

The simplicity of per-element parity generation allows for easierrecovery of the sequential component (bonus bit, e.g., a PRBS value) foran element of data, anywhere in the data path by simply XORing the dataand parity bits to get the bonus bit, e.g., a PRBS value, for thatlocation in the sequence. This is especially useful when midstreammodifications to the data are performed and/or required. All that isneeded is to read the data, derive the bonus bit from current data andparity values, modify the data, and use the bonus bit to calculate amodified data parity to accompany the new data value.

According to one embodiment, a system may comprise a processor and logicintegrated with and/or executable by the processor, the logic beingconfigured to: receive data comprising a plurality of data elements,each data element comprising one or more bits, and pass each dataelement along with a corresponding parity bit 412 to the input 404 ofthe data path 402. The system may also include a first binary sequencegenerator 408 configured to create a binary sequence comprising aplurality of bonus bits, wherein a total length of the binary sequenceis equal to or greater than a maximum burst size of the data, and afirst XOR module 410 configured to provide a XOR calculation using bitsof each data element of the data with a bonus bit from the binarysequence to produce a parity bit 412 for each data element.

In a further embodiment, the logic may be further configured to: receiveeach data element along with its corresponding parity bit 412 at theoutput 406 of the data path 402, and analyze (such as by using ananalysis module 418) a result to determine whether an error has occurredto the data in the data path 402. In addition, the system may include asecond binary sequence generator 414 configured to create the binarysequence at the output 406 of the data path 402 and a second XOR module416 configured to XOR together bits of each data element along with itscorresponding parity bit 412 and a bonus bit from the binary sequence toproduce the result.

Now referring to FIG. 5, a flowchart of a method 500 is shown accordingto one embodiment. The method 500 may be performed in accordance withthe present invention in any of the environments depicted in FIGS. 1-4,among others, in various embodiments. Of course, more or less operationsthan those specifically described in FIG. 5 may be included in method500, as would be understood by one of skill in the art upon reading thepresent descriptions.

Each of the steps of the method 500 may be performed by any suitablecomponent of the operating environment. For example, in variousembodiments, the method 500 may be partially or entirely performed by adata path controller, or some other device having one or more processorstherein. The processor, e.g., processing circuit(s), chip(s), and/ormodule(s) implemented in hardware and/or software, and preferably havingat least one hardware component may be utilized in any device to performone or more steps of the method 500. Illustrative processors include,but are not limited to, a CPU, an ASIC, a FPGA, etc., combinationsthereof, or any other suitable computing device known in the art.

As shown in FIG. 5, method 500 may initiate with operation 502, wheredata comprising a plurality of data elements is received. Each dataelement comprises one or more bits of data. Accordingly, the dataelement may be a bit, a byte, a word, a double word, or any othercollection of data as would be known in the art. The data may bereceived as a stream, in chunks, in bursts, or in any other fashionknown in the art.

In operation 504, a binary sequence is created. The binary sequencecomprises a plurality of bonus bits using a first binary sequencegenerator, a total length of the binary sequence being equal to orgreater than a maximum burst size of the data.

The binary sequence may be configured so as to not coincide with any bitsequence of the data while in the data path. Therefore, in oneembodiment, the binary sequence may be decimal-based as opposed tohexadecimal-based. In other approaches, any other methodology ofdifferentiating the binary sequence from the data elements in the datapath may be used, as known in the art.

In operation 506, a first XOR module is used to XOR together (in a XORcalculation) bits of each data element of the data with one or morebonus bits from the binary sequence to produce a parity bit for eachdata element.

In a further embodiment, meta data (such as tags, flags, etc.) may beincluded in the XOR calculation to produce the parity bit. In this way,not only is the data in the data element and the sequence of the dataprotected, but also any meta data that is desired to be included in theXOR calculation may also be protected from errors.

In one embodiment, when one or more FPGAs are included in the data path,the data element may be a byte to take advantage of the FPGA's nativeability to store a byte of data with a parity bit. Of course, in othermemory or data path components, some other advantages may be drawn fromusing different sized data elements, any of which are compatible withthis method 500.

In operation 508, each data element is passed along with itscorresponding parity bit to an input of a data path. The data path, invarious embodiments, may include any desired functionality, such as afirst-in-first-out (FIFO) buffer, a store and forward buffer, a RAM toother such memory, sequential logic, a flash memory such as nonvolatileRAM, etc., or any other data path component known in the art.

In one embodiment, the method 500 may further include receiving eachdata element along with its corresponding parity bit at an output of thedata path, creating the binary sequence using a second binary sequencegenerator, using a second XOR module to XOR together bits of each dataelement along with its corresponding parity bit and a bonus bit from thebinary sequence (in a second XOR calculation) to produce a result, andanalyzing the result to determine whether an error has occurred to thedata in the data path. In this way, after the data has passed throughthe data path, such as being stored in and retrieved from a RAM, theconsistency of the data, the sequence of data, and any included metadata may be checked for errors.

According to one approach, analyzing the result may include determiningwhether the result is zero. A zero result would indicate that no erroroccurred to the data while in the data path, and a non-zero result wouldindicate that an error occurred to the data while in the data path. Thetype of error and where it exactly occurred may or may not be discoveredfrom the result.

After analyzing the result, error(s) may be reported to some componentor module, such as a controller, administrator, etc. The error(s) may bereported alone or in combination with a location indicated as somewherein the data path.

In another embodiment, the second binary sequence generator may bematched to the first binary sequence generator, in order to provide theexact same binary sequence at the input and the output of the data pathto allow for the error check to be performed.

According to another embodiment, the data which exits the output of thedata path may exist in burst sizes that are equal to burst sizes of thedata that entered the input of the data path. In this way, the sequenceof the data entering and exiting the data path may be checked.

In another approach, the first binary sequence generator and/or thesecond binary sequence generator may each comprise one or more LFSRs.Also, the binary sequence may be a pseudo-random binary sequence, arandom binary sequence, a partially repeating binary sequence.

In this or any other approach, the binary sequence may be unlikely(i.e., have less than a 0.1% chance, 0.01% chance, 0.0001% chance, etc.)to match any sequence of bits in the data while in the data path.Sequence aliasing probability is highly dependent on the systemimplementation, and therefore the exact chance of matching may only becalculated from the actual implementation. For example, in systems withaddresses following a normal binary count, the probability of afault-produced sequence aliasing a PRBS is virtually zero. When usingsuch binary sequences, the binary sequence would have virtually nochance of matching any sequence of bits in the data while in the datapath. In this approach, the binary sequence would not be inadvertentlyduplicated by the data while in the data path, which would result inadditional problems and confusion. This is a property of pseudo-randombinary sequences that are generated from LFSRs, and therefore using oneor more LFSRs is preferred in one embodiment.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an ASIC, a FPGA,etc. By executable by the processor, what is meant is that the logic ishardware logic; software logic such as firmware, part of an operatingsystem, part of an application program; etc., or some combination ofhardware and software logic that is accessible by the processor andconfigured to cause the processor to perform some functionality uponexecution by the processor. Software logic may be stored on local and/orremote memory of any memory type, as known in the art. Any processorknown in the art may be used, such as a software processor module and/ora hardware processor such as an ASIC, a FPGA, a CPU, an integratedcircuit (IC), a graphics processing unit (GPU), etc.

Some advantages over other approaches to detecting data and sequencingfaults in complex controllers with multiple memory stages includes: 1)greater fault coverage than simple data parity by using a sequencingcomponent in the parity calculation; 2) more generality than data andaddress parity schemes, since addressing (and therefore address parity)may not be consistent across the data path; 3) less complexity than CRCgeneration and checking, especially when midstream data modificationsoccur; 4) low resource utilization and high performance when using LFSRsto provide the sequencing component of the parity generation andchecking; 5) minimal overhead by using resources built into memoryblocks specifically for parity storage, such as in FPGAs. Otheradvantages may also be present which are not specifically addressedherein.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer to offer service on demand.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A computer program product, the computer programproduct comprising a non-transitory computer readable storage mediumhaving program instructions embodied therewith, the program instructionsreadable by a processor, executable by the processor, or readable andexecutable by the processor to cause the processor to: receive, by theprocessor, data comprising a plurality of data elements, each dataelement comprising one byte; create, by the processor, a binary sequencecomprising a plurality of bonus bits using a first binary sequencegenerator, a total length of the binary sequence being equal to orgreater than a maximum burst size of the data, wherein the first binarysequence generator comprises one or more linear feedback shift registers(LFSRs); use, by the processor, a first parity module to provide aparity calculation using bits of each data element of the data with abonus bit from the binary sequence, the parity calculation producing aparity bit for each data element; pass, by the processor, each dataelement along with its corresponding parity bit to an input of a datapath; receive, by the processor, each data element along with itscorresponding parity bit at an output of the data path, wherein dataexits the output of the data path in burst sizes that are equal to burstsizes of the data that entered the input of the data path; create, bythe processor, the binary sequence using a second binary sequencegenerator, wherein the second binary sequence generator is matched tothe first binary sequence generator; use, by the processor, a secondparity module to produce a result based on bits of each data elementalong with its corresponding parity bit and a bonus bit from the binarysequence; and analyze, by the processor, the result to determine whetheran error has occurred to the data in the data path.
 2. The computerprogram product of claim 1, wherein analyzing the result comprisesdetermining whether the result is zero, wherein a zero result indicatesthat no error occurred to the data while in the data path, and wherein anon-zero result indicates that an error occurred to the data while inthe data path.
 3. The computer program product of claim 1, wherein thesecond binary sequence generator comprises one or more LFSRs, andwherein the binary sequence is a pseudo-random binary sequence.
 4. Thecomputer program product of claim 1, wherein the first binary sequencegenerator and the second binary sequence generator are configured toproduce the binary sequence to have less than a 0.1% chance of matchingany sequence of bits in the data while in the data path.
 5. The computerprogram product of claim 1, wherein the data path comprises at least oneof: a first-in-first-out (FIFO) buffer, a store and forward buffer, arandom access memory (RAM), sequential logic, and a flash memory, andwherein each data element is one byte in length.
 6. The computer programproduct of claim 1, wherein meta data is included in the paritycalculation to produce the parity bit.
 7. A system, comprising: ahardware processor; and logic integrated with the hardware processor,executable by the hardware processor, or integrated with and executableby the hardware processor, the logic being configured to: receive datacomprising a plurality of data elements, each data element comprisingone byte; create a binary sequence comprising a plurality of bonus bitsusing a first binary sequence generator, a total length of the binarysequence being equal to or greater than a maximum burst size of thedata, wherein the first binary sequence generator comprises one or morelinear feedback shift registers (LFSRs); use a first parity module toprovide a parity calculation using bits of each data element of the datawith a bonus bit from the binary sequence, the parity calculationproducing a parity bit for each data element; pass each data elementalong with its corresponding parity bit to an input of a data path;receive each data element along with its corresponding parity bit at anoutput of the data path, wherein data exits the output of the data pathin burst sizes that are equal to burst sizes of the data that enteredthe input of the data path; create the binary sequence using a secondbinary sequence generator, wherein the second binary sequence generatoris matched to the first binary sequence generator; use a second paritymodule to produce a result based on bits of each data element along withits corresponding parity bit and a bonus bit from the binary sequence;and analyze the result to determine whether an error has occurred to thedata in the data path.
 8. The system as recited in claim 7, whereinanalyzing the result comprises determining whether the result is zero,wherein a zero result indicates that no error occurred to the data whilein the data path, and wherein a non-zero result indicates that an erroroccurred to the data while in the data path.
 9. The system as recited inclaim 7, wherein the second binary sequence generator comprises one ormore LFSRs, and wherein the binary sequence is a pseudo-random binarysequence.
 10. The system as recited in claim 7, wherein the first binarysequence generator and the second binary sequence generator areconfigured to produce the binary sequence to have less than a 0.1%chance of matching any sequence of bits in the data while in the datapath.
 11. The system as recited in claim 7, wherein the data pathcomprises at least one of: a first-in-first-out (FIFO) buffer, a storeand forward buffer, a random access memory (RAM), sequential logic, anda flash memory, and wherein each data element is one byte in length. 12.The system as recited in claim 7, wherein meta data is included in theparity calculation to produce the parity bit.
 13. A method, comprising:receiving, by a processor, data comprising a plurality of data elements,wherein each data element is one byte in length; creating, by theprocessor, a binary sequence comprising a plurality of bonus bits usinga first binary sequence generator, a total length of the binary sequencebeing equal to or greater than a maximum burst size of the data; using,by the processor, a first exclusive-or (XOR) module to provide a XORcalculation using bits of each data element of the data with a bonus bitfrom the binary sequence, the XOR calculation producing a parity bit foreach data element; passing, by the processor, each data element alongwith its corresponding parity bit to an input of a data path; receiving,by the processor, each data element along with its corresponding paritybit at an output of the data path, wherein data exits the output of thedata path in burst sizes that are equal to burst sizes of the data thatentered the input of the data path; creating, by the processor, thebinary sequence using a second binary sequence generator, wherein thesecond binary sequence generator is matched to the first binary sequencegenerator; using, by the processor, a second XOR module to XOR togetherbits of each data element along with its corresponding parity bit and abonus bit from the binary sequence to produce a result; and analyzing,by the processor, the result to determine whether an error has occurredto the data in the data path comprising determining, by the processor,whether the result is zero, wherein a zero result indicates that noerror occurred to the data while in the data path, wherein a non-zeroresult indicates that an error occurred to the data while in the datapath.